Empirical and theoretical models for prediction of soil thermal conductivity: a review and critical assessment
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09 jul 2020
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Categoría del artículo: Original Study
Publicado en línea: 09 jul 2020
Páginas: 330 - 340
Recibido: 06 jun 2020
Aceptado: 17 jun 2020
DOI: https://doi.org/10.2478/sgem-2019-0053
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© 2020 Adrian Różański, et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
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Advantages, disadvantages and comments on considered empirical models (Różański, 2018)_
Model | Advantages | Disadvantages | Comments |
Simple formula; for every type of soil | Equations do not take into account the quartz content which has the largest contribution in overall value of | Thermal conductivity in dry state cannot be determined | |
Can be used for frozen soils; relatively high quality of prediction; for every type of soil | Possible inaccuracy for dry soil (±20%) | Empirical relations valid for | |
Simple formula; for every type of soil | Weak prediction for soils with low water content | The shape of the | |
For every type of soil; includes the type of soil and the shape of grains | The course of the | Modification of the | |
For every type of soil; very good reflection of thermal conductivity for fine-grained soils with very low water content; the type of soil is taken into account | Unknown influence of the type of soil on the conductivity in the dry state | Modification of the Johansen method with respect to the Kersten number and dry soil conductivity | |
Simple formula; good quality of prediction | Limited applicability | Only for sands with a high quartz content | |
Simple formula; for every type of soil; includes the effect of the dry density on thermal conductivity | For the analysed soils, the model clearly overestimated the values of | Dry soil conductivity should be computed using empirical relation proposed in | |
Simple formula; for every type of soil; good quality of prediction | Lack of correlation formulas for determining model parameters | Modification of the Johansen method with respect to the Kersten number |
Different approaches used for evaluation of the Kersten number Ke and the conductivity of dry and saturated soil_
Coarse-grained soil: | |||
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Advantages, disadvantages and comments on the considered theoretical models (Różański, 2018)_
Determination of the range of possible thermal conductivity values of porous media (soils); simple formula | Rough estimate | For coarse soils, due to the contrast between the thermal conductivity of the components, these bounds are very wide | |
For every type of soil | Weak prediction for dry soils or with low water content | Should not be applied to the soils with relatively high porosity | |
For every type of soil | Complicated formula; need to use nomograms | Not applicable to dry soils; possible overestimation of thermal conductivity results if Gemant formula is not used to determine the thermal conductivity of the soil skeleton | |
For every type of soil; can be used for partially or fully frozen soils | Need to assume values of shape factors | For good predictions, one should incorporate in | |
For every type of soil; can be used for different temperatures | Very complex formula; Certain parameters should be determined on the basis of laboratory tests’ results | Possible underestimation of thermal conductivity for dry soils | |
Includes the impact of many factors on the thermal conductivity of the porous media | Complex formula; a series of laboratory tests have to be performed | Lack of formulas from which model parameters can be computed | |
High accuracy of prediction | Complex formula; Underestimation of results by a constant factor, about 1.58 | Only for sandy soils with a porosity higher than 0.333 |